Moscow is getting crowded with all the visitors. On Sunday, some members of the Washington Ballet who are performing in the Soviet Union were touring the Kremlin when they ran into Michael Kahn, the artistic director of the Shakespeare Theatre at the Folger. Kahn is there with the Acting Company of New York performing "Five by Tennessee," five one-act Tennessee Williams plays. Before coming to the Folger, Kahn was artistic director of the Acting Company for 10 years.

Out and About

Andrew Lloyd Webber's "Phantom of the Opera, a smash hit in London and New York, is on its way to becoming one of the biggest hits of the Kennedy Center and it doesn't open there until May 28. It promises to be such a moneymaker that with current advance ticket sales of more than $5 million for the summer run through Aug. 3, the show is expected to break Kennedy Center box office records. In addition to all those profits, the show's producer, Cameron Mackintosh, has told the Kennedy Center it can raise additional money for itself by holding the first benefit performance of the show's run on May 29. It will include a supper dance on the stage of the Eisenhower Theater following the Opera House production ...

Hospital Report: Actress Mary Martin, who took her own advice as "Peter Pan" and has never seemed to grow up, has been hospitalized for tests. A publicist for the 76-year-old star of "Peter Pan," "The Sound of Music" and "South Pacific" refused to say where she was hospitalized or the reason for the tests. Richard Grant, a publicist for Martin's son, "Dallas" star Larry Hagman, said only, "Miss Martin has been hospitalized for tests. That is all I will confirm. In this case we just don't choose to give out the information." Martin, who had been seriously injured in a taxi-van crash in 1982, was a 1989 Kennedy Center Honoree ... Rep. Raymond McGrath, who was admitted to the Walter Reed Army Medical Center Thursday with a blood clot in his lung, was reported to be resting yesterday and taking blood-thinning drugs. A spokesman for the New York Republican said the clot was already breaking up when it was discovered. He is expected to be released from the hospital by midweek ...

The Freer Gallery of Art has received a pledge of $1.5 million toward the renovation of the museum from a Japanese consortium that includes Ikuo Hirayama, an internationally known artist and president of the National University of Fine Art and Music in Tokyo. It represents the largest gift the national museum of Asian art at the Smithsonian has received since it opened in 1923 with a bequest from Detroit industrialist Charles Lang Freer, who gave the Smithsonian his art collection, a building fund and an endowment. The gift will be used toward reinstallation of the Freer collection in newly restored galleries, part of a major renovation project that began in 1988 ...

The USO and Philip Morris Cos. sent off 100,000 packages of foods and other products yesterday to troops stationed in the Persian Gulf region. The packages contained items from cassette tapes to M&M's to Kool Aid and powdered soft drinks and coffees, but absolutely no cigarettes ...